package dfs;

import java.util.LinkedList;

public class 回溯 {

    public int numTilePossibilities(String tiles) {
         if (tiles=="" || tiles.length()==0)
             return 0;
        LinkedList list = new LinkedList();
        dfs(tiles,0,list);
        return 0;
    }

    private void dfs(String tiles, int k, LinkedList list) {

        for (int i = 0; i < tiles.length(); i++) {
             list.add(tiles.charAt(i));

        }
    }

}
